Diversity of Organisms
5 Kingdoms of Classification
- Monera (Prokaryotae) - Bacteria; most numerous organism on earth
- Protista (Protoctista) - Small single celled organisms such as amoeba
- Fungi - single celled or multicellular heterotrophic organisms
- Plant - multicellular photosynthetic organisms
- Animal - multicellular heterotrophic organisms
Monera
All species of Bacteria.
Bacteria are prokaryotic: They have no membrane bound nucleus or membrane bound organelles.
3 Main Types of Bacteria
- Spherical (coccus/cocci)
Round
e.g. Staphylococcus Aureus which is naturally on skin
- Spiral (Spirillum/Spirilla)
Spiral
e.g. Helicobacter Pylori which infect stomach and duodenum
- Rod (bacillus/Bacilli)
Rod
e.g. E. Coli
Bacterial Reproduction
= Binary Fission; asexual reproduction in bacteria
1) DNA and plasmid replicates
2) Cell increases in size
3) Each replicate moves to either side of the cell
4) Cell wall and cell membrane pinch inwards down the middle
= Cell division
Endospore Formation
Endospore is a thick, tough walled, dormant and dehydrated bacteria which is formed in unsuitable conditions
Its a survival method
1) Nutrients begin to run out
2) Assymetrical binary fission occurs
3) Smaller cell is engulfed by the larger
4) Outer cell forms thick wall
5) Tough walled cell = endospore
*Germinates when conditions become favourable again
Nutrition in Bacteria
- Autotrophic - Produce own food
Chemosynthesis Bacteria: Use chemicals to produce food
e.g. Nitrifying Bacteria
Photosynthesis Bacteria: Converts CO2 into Glucose through the use of light
e.g. Purple-Sulfur Bacteria
- Heterotrophic - Obtain food and nutrients from other organisms
Saprophytic Bacteria: Feed from dead organisms, bacteria of decay
Parasitic Bacteria: Feed off living/host
e.g. E. Coli
Factors Affecting Growth of Bacteria
- Temperature: Affects enzymes. However many types of bacteria have adapted to extreme temperaures
- Oxygen Concentration: However some bacteria are anaerobic
- pH
- External Solute in Cells: Can cause a decrease of water concentration in cell
- Pressure
Growth Curve of Microorganisms
Lag: Adjusting to new conditions
Log: Microorganism reproduction is exponential
Stationary: DR=BR Nutrients begin to run out and toxins increase
Decline: DR > BR
Survival: Some bacteria produce endospores
Food Processing
Changing of raw materials into food which is fit for consumption
- In batch processing batch is taken out once the bacteria reach stationary phase and new substrates are added in.
- In continuous flow it is maintained at log phase and products are constantly taken out whilst new raw materials are added in.
Antibiotics
Chemicals produced by microorganisms that prevent the growth of or kill other microorganisms used as medication to fight infections
*Overuse of Antibiotics
- Bacteria mutate and develop resistance
- e.g. MRSA
Beneficial Bacteria
- Bacteria which are good for the environment
Lactic Acid Bacteria
- Curdling milk for dairy products
Bacteria in the large intestine
- E.Coli, symbiotic relationship
- Can be used in genetic engineering
Harmful Bacteria
Pathogenic: Organism that causes disease
Strep Throat Bacteria
- Bacteria that leads to sore throat and scarlet fever
Tuberculosis Bacteria
- Infection of the lung
Fungi
- No autotrophic fungi
- Eukaryotic
- Can be single/multicellular
- Spend most of its life Haploid
- Cell walls = chitin
Nutrition
Saprophytic Fungi: Obtain their food from dead organic matter
Parasitic Fungi: Obtain their food from a living host
Yeast
Structure;
- Single celled
- Cell wall made of chitin
- Granular cytoplasm
Reproduction:
1) Small extension of cell
2) Nucleus divides by mitosis and moves into new part of cell
3) New cell can break off or form another bud
Rhizopus (bread mould)
- Saprophytic Fungi
- Thread like structures = Hyphae
* Sporangium releases spores for asexual reproduction
Rhiziods:
- Anchor
- Release digestive enzymes onto substrates
- Absorb nutrients from substrates
* All the hyphae together are called mycellium; all the cells in a mycellium are haploid.
Sexual Reproduction in Rhizopus
- Occurs when nutrients are running out
1) Two hyphae of opposite strains grown close together
2) Swelling occurs towards either hyphae, swelling is called progametangia
3) These join together to form a gametangium
4) Fertilisation occurs
5) Diploid nuclei form = Zygospore
Zygospore;
- Tough walled structure for harsh conditions
- Germinates in suitable conditions, undergoes meiosis first so that it returns to haploid
Economic Importance of Fungi
Beneficial: Button mushrooms, yeast
Harmful: Death cap, rhizopus (spoils food)
Investigate the growth of leaf yeast using agar plates and controls
Aseptic technique: procedure where contact with, or contamination by, microorganisms is avoided.
Sterility: State of being free from microorganisms
- Sterilise agar solution by boiling it
- Set up 3 petri dishes; one with normal leaf, one with disinfected leaf, one with no leaf (negative control)
- Leave dishes in an incubator at 25 degrees for 3 days
- Pink colonies will form on the test
- Nothing should form on the controls
Protista
- Mostly single cellular
- Eukaryotic
- Great variation
- Can be heterotrophic/autotrophic/parasitic
- Water based
Contractile Vacuole: For osmoregulation, ATP pumps water to contractile vacuole in the cell. Once full it moves towards the cell membrane and water is released.
Cytoplasm: Made up in the endoplasm and the more viscous outer ectoplasm
Pseudoplasm: For movement and feeding
Viruses
- Not cells, they are DNA or RNA surrounded by a protein coat
- Obligate parasites; can only replicate inside a host cell
Are they living?
- Demonstrate organisation and response
- Do not demonstrate nutrition as they don't metabolise food for energy
- Do not show excretion, they have no direct waste
- Do not show reproduction as they cannot reproduce on their own
Shapes:
- Rod shaped virus
e.g. tobacco mosiac virus
- Round virus
e.g. flu virus
- Complex virus
e.g. bacteriophage - infects bacteria
Replication of Viruses
1) Binds to complementary proteins on host cell
2) Either injects DNA/RNA or whole virus enters
3) Takes control of cell nucleus to make copies of itself
4) Uses cell machinery to make new viruses
5) Released by budding through cell or bursting cell open
Harmful Viruses
In Humans: HIV, Flu Virus
In Animals: Foot and mouth virus, Rabies virus
In Plants: Tobacco/Tomato Mosaic virus
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